Automatic Transmission - Overhaul & Testing - 4l80e Chevrolet Cab & Chassis K2500

APPLICATION

APPLICATION

IDENTIFICATION

All transmissions have a metal identification plate attached to the rear face of transmission case. (Scheme 1)

Scheme 1

DESCRIPTION

The Hydra-Matic 4L80-E transmission is a fully automatic 4-speed unit consisting primarily of a hydraulic torque converter and converter clutch. Transmissions have dual stators inside the torque converter. Transmission uses a gear-type pump to supply all hydraulic pressure needed for operation.

Other internal parts include the following: 5 multiple disc clutches, a roller clutch, a sprag clutch, 2 bands and 3 compound planetary gear sets.

The Hydra-Matic 4L80-E also uses 2 electronic shift solenoids controlled by Powertrain Control Module (PCM) or Transmission Control Module (TCM). The transmission uses 2 speed sensors instead of a governor.

LUBRICATION & ADJUSTMENTS

See GENERAL MOTORS LIGHT TRUCKS & VANS TRANSMISSION SERVICING article.

ON-VEHICLE SERVICE

The following components can be serviced without removing transmission from vehicle

1. Converter-To-Flexplate Bolts
2. Filler Pipe
3. Front Servo
4. Rear Servo
5. Rear Extension Housing
6. Shift Control Cable
7. Solenoids
8. Speedometer Driven Gear & Seal
9. Speed Sensors
10. Transmission Pan & Filter
11. Valve Body
12. Wiring Harness
13. 3-4 Accumulator Assemblies

VALVE BODY

See OIL PUMP & VALVE BODY under TRANSMISSION DISASSEMBLY.

OIL COOLER FLUSHING

1. If available, fill line flusher with solution and install Oil Cooler and Line Flusher (J-35944) to top transaxle cooler line on transaxle. Follow manufacturer's instructions to flush oil cooler and cooler lines.
2. If flusher tool is not available, flush cooler and cooler lines with a mixture of clean solvent and water. Flush cooler in both directions until all old fluid and debris are removed. If necessary, replace plugged or damaged cooler and/or lines.

TROUBLE SHOOTING

Note. For testing and diagnostic procedures of electronic components, see AUTO TRANS DIAGNOSIS - 4L60/4L80 article.

QUICK CHECK

1. Check the level and condition of the transmission fluid. Check the PCM or TCM memory for any stored trouble codes. Refer to the appropriate DIAGNOSIS article. If no trouble codes are present, go to next step. If codes are present, diagnose and repair all computer-related trouble codes. Clear PCM or TCM trouble code memory.
2. Perform road test. See «ROAD TEST»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e__road-test) under TESTING. During road test, record shift points. If shift point timing or shifting is incorrect, go to the appropriate DIAGNOSIS article.
3. If shift(s) is too harsh or too soft, see procedures for «HYDRAULIC PRESSURE TESTS»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e__hydraulic-pressure-tests) under TESTING. For specific complaints, see appropriate condition(s) listed under «SYMPTOM DIAGNOSIS»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e__symptom-diagnosis) .

SYMPTOM DIAGNOSIS

Note. Models with gasoline engines use Powertrain Control Module (PCM) computer. Models with diesel engines use Transmission Control Module (TCM) computer. These computers control TCC, force motor (hydraulic pressure) and shift solenoids "A" and "B".

Fluid Out Of Vent Or Foaming

Transmission overfilled. Fluid contaminated with antifreeze or engine overheating. Filter not seated. Cross-channel leak allowing pressure to leak in to vent area of pump cover.

Transmission Overheats

Low fluid or blocked radiator. TCC stuck in apply or release. Broken TCC valve spring. Cross channel leakage in pump cover. Pressure regulator stuck in high demand. Blocked oil cooler. Problem with converter limit valve assembly. Loss of fluid. Problem with stator(s) or turbine seals.

Reduced Internal Lubrication

Cross channel leakage in pump cover. Pressure regulator stuck in high demand. Damaged oil pump mounting gasket. Stuck closed converter limit valve assembly (under heavy load).

High Or Low Line Pressure

Incorrect fluid level. Oil pump assembly seals or gears damaged. Pump drive shaft damaged. Pressure regulator valve spring damaged, pressure regulator valve nicked or scored. Pressure relief valve spring damaged. Pump cover leaking (bolts loose). Force motor off or on at all times. Loose connection at PCM or TCM. Possible trouble Code 73.

Inoperative In Drive

1. Low fluid level. Low fluid pressure. Manual linkage misadjusted or disconnected. Damaged torque converter. Leaking or damaged transmission case seals or gaskets. Damaged oil pump drive shaft or pump assembly. Broken bearing, pinion or carrier. Roller clutch damaged or locked.
2. Piston or seal damaged in forward clutch assembly. Forward clutch assembly clutch plates burned or missing, or check ball capsule leaking or missing. Burned reaction plate (due to lack of lubrication), broken snap ring or worn gear teeth.
3. Rear gear set assembly pinions, internal ring gear or sun gear damaged. Main shaft damaged. Parking pawl spring broken. Turbine shaft ball not seating.

Vehicle Moves Forward In "N"

Mis-positioned or stuck manual valve. Problem with forward clutch assembly.

Engine Stall

Seized forward clutch, 4th clutch or overrun clutch assembly. TCC stuck on or dragging.

No Torque in Reverse & 3rd

Broken forward clutch hub, housing or snap ring.

Locked in Park

Damaged parking pawl; binding, weak spring or stretched rod.

Vehicle Moves in Park

Manual linkage damaged or disconnected. Broken parking pawl spring, parking pawl or parking pawl gear assembly. Park actuator spring damaged.

Slips in Reverse

Low fluid pressure. Reverse servo seal damaged. Reverse reaction drum splines stripped.

No Reverse

Low fluid pressure. Reverse servo not correctly assembled, piston or seal damaged, or incorrect apply pin. Damaged rear band. Direct clutch assembly clutch plates burned or missing, or check ball capsule leaking or missing.

Slips in "D"

Low fluid level. Low fluid pressure.

No 1st Gear in "D4"

Low roller assembly not attached or race broken. Broken center support race or splines. Damaged case near center support. Center support snap rings not seated.

No 1st Gear in "D2" Or "D3"

Low roller assembly not attached or race broken. Broken center support race or splines. Damaged case near center support. Center support snap rings not seated. Stuck front band.

No 1st Gear in "D1"

Low roller assembly not attached or race broken. Broken center support race or splines. Damaged case near center support. Center support snap rings not seated. Broken housing, or mispositioned or broken rear band anchor pin. Misaligned detent lever.

No 1-2 Shift in "D4" (1st Gear Only)

Output or input speed sensor reads zero. Sun gear splines damaged or missing.

1st & 2nd Gear Only

Solenoid "B" stuck off or not connected to PCM or TCM. Dirt in filter, leaking "O" ring or no supply voltage to solenoid "B". Stuck 2-3 shift valve. Possible trouble Code 68, 81, 85 or 87.

1st & 4th Gear Only (Manual 2nd & 3rd Only)

Solenoid "A" stuck off. Dirt in filter, PCM or TCM not grounded, leaking "O" ring, no supply voltage to solenoid "A" or wire disconnected. Stuck 1-2 shift valve. Possible trouble Code 68, 82 or 85.

Late 1-2 Shift

Problem with input and/or output speed sensor(s). Faulty digital ratio adapter (2WD only). Incorrect PROM calibration. Possible trouble Code 24, 28 or 85.

No Engine Braking in "D1"

Problem with rear band assembly. Damaged main or output shafts.

No 2nd Gear

Intermediate clutch feed cup plug missing. Problem with intermediate clutch and center support assembly. Damaged intermediate sprag. Broken direct clutch housing or snap ring.

2nd Gear Only

Possible trouble Code 24, 53, 75 and 81.

No Torque in 2nd

Worn or damaged intermediate sprag.

Starts in 2nd Gear

Seized intermediate clutch plates. Problem with direct clutch or center support assemblies. Stuck 1-2 shift valve. PCM- or TCM-related problem. Possible trouble Code 82.

No 2nd Gear Braking in "D2"

Problem with direct clutch housing or front band assemblies.

No Engine Braking in "D2"

Problem with rear gear set assembly. Damaged main or output shafts.

No Overrun Braking in "D2"

Problem with overrun clutch or reaction sun gear assemblies.

No 1st Gear in "D3"

Low roller assembly not attached or race broken. Broken center support race or splines. Damaged case near center support. Center support snap rings not seated. Applied front band.

No 2nd Gear in "D3"

Intermediate clutch feed cup plug missing. Problem with intermediate clutch and center support assembly. Damaged intermediate sprag. Broken direct clutch housing or snap ring.

No 3rd Gear in "D3"

Direct clutch feed cup plug missing. Problem with direct clutch and center support assembly. Broken direct clutch housing or snap ring. Solenoid "B" stuck off. Dirt in filter, PCM or TCM not grounded, leaking "O" ring, no supply voltage to solenoid "B" or wire disconnected. Stuck 2-3 shift valve. PCM or TCM problem. Possible trouble Code 81, 85 or 87.

Starts in 3rd Gear

Seized forward clutch or oil holes in driving hub plugged. Damaged or seized direct clutch assembly.

No Engine Braking in "D3"

Damaged main shaft or main shaft bushing.

2nd & 3rd Gear Only

Stuck 1-2 shift valve. Solenoid "A" off. Dirt in filter, PCM or TCM not grounded, leaking "O" ring, no supply voltage to solenoid "A" or wire disconnected. Possible trouble Code 68, 82 or 85.

No 4th Gear

Problem with 4th clutch or overrun clutch related assemblies. 2-3 shift valve stuck. Solenoid "B" off. Dirt in filter, PCM or TCM not grounded, leaking "O" ring, no supply voltage to solenoid "B" or wire disconnected. Possible trouble Code 21, 22, 28, 68, 75 or 81.

Starts in 4th Gear

Solenoid "B" stuck on. Dirt in filter, PCM or TCM signal wire grounded. Possible trouble Code 86.

Note. Digital ratio adapter receives signals from electronic speedometer and sends them to PCM/TCM.

Incorrect Shift Points

Problem related to PCM or TCM signal inputs from TPS, speed sensors or pressure switch manifold. Faulty digital ratio adapter (2WD only). Possible trouble Code 21, 22, 24, 28 or 85. Incorrect tire size, axle ratio or PROM.

Harsh Shifts

High or low line pressures. Force motor stuck off. Accumulator piston seals damaged or piston springs missing. Accumulator cover bolts improperly tightened or gaskets mispositioned. Missing check balls. Incorrect PROM calibration. Possible trouble Code 21, 22, 24, 28, 53, 68, 73, 75, 81 or 85.

Harsh Shifts ("D" To "R")

Blocked direct lube exhaust. Forward clutch spring not working. Direct clutch snap ring broken or not seated. Plugged direct clutch check ball.

Harsh Shifts (3-4 Shift)

Binding 4th clutch spring assembly. Plugged air bleed hole. 4th clutch case bolt blocking oil feed hole.

Harsh Shifts (4-3 Shift)

4th clutch snap ring not seated. 4th clutch spring assembly not working. Plugged 4th clutch housing cup plug. 4th clutch case bolt blocking oil feed hole. Blocked direct lube exhaust port.

Harsh Shifts ("D4" To "D3", "D2" or "D1")

Overrun clutch return spring assembly not working. Plugged overrun clutch housing check ball. Snap ring not seated.

Soft Shifts

Low line pressures. Force motor stuck on. Accumulator piston seals damaged or piston springs missing. Accumulator cover bolts improperly tightened or gaskets mispositioned. PCM or TCM failure. Incorrect PROM calibration. Possible trouble Code 73.

Soft Shift (Into "R")

Plugged direct clutch oil feed. Blocked direct lube exhaust port.

Soft Shift (R To "D")

Direct clutch spring not working, large snap ring not seated or plugged check ball.

Soft Shift (2-1)

Intermediate clutch spring assembly not working. Center support snap ring not seated. Center support air bleed blocked.

Soft Shift (2-3)

Plugged direct clutch oil feed. Blocked direct lube exhaust port.

Soft Shift (3-2)

Direct clutch spring not working, small snap ring not seated or plugged check ball.

Soft Shift ("D3" To "D2")

Missing check ball. Incorrect orifice sizes.

No "D2" To "D1" Shift

Broken or disconnected rear band. Incomplete travel of detent lever.

No "D3" To "D2" Shift

Broken or disconnected front band.

No Converter Clutch Apply

Verify proper PCM or TCM operation and vehicle wiring. Damaged wiring harness or pinched wires. Brake switch not working or misadjusted. Solenoid inoperative. Oil pump valve assembly converter clutch shift valve stuck. Converter clutch apply valve stuck. Leaking solenoid "O" ring or blocked screen. Inspect torque converter for external leaks at hub weld area, or unbalanced or contaminated fluid. Turbine shaft seals damaged. Oil pump drive shaft seal damaged. Converter clutch release exhaust orifice cup plug not seated or damaged. Possible trouble Code 24, 27, 28, 37, 39, 53, 68, 75, 81 or 83.

Converter Clutch Does Not Release

PCM or TCM-controlled TCC solenoid stuck on or does not exhaust. Control valve assembly converter clutch apply valve stuck in apply position. Faulty PCM or TCM. Possible trouble Code 83.

Converter TCC Apply Soft Or Slipping

Leaking turbine shaft seals. Worn oil pump body bushing. Leaking oil hole transfer cup plug. Faulty TCC solenoid. Low fluid pressure.

Converter Clutch Apply Time Incorrect

Incorrect output speed sensor, engine speed or throttle position sensor signal. Faulty PCM or TCM. Faulty pressure switch or temperature sensor. Incorrect coolant or transmission temperature (diesel engine) signal. Possible trouble Code 14, 15, 21, 22, 24, 28, 58, 59 or 68. Problem with digital ratio adapter (2WD only). Faulty brake switch circuit or ignition module (gasoline vehicles) or faulty tachometer (diesel vehicles.)

CLUTCH & BAND APPLICATION CHART

TESTING - ELECTRONIC SELF-DIAGNOSTICS & ELECTRONIC TESTING

Note. Models with gasoline engines use Powertrain Control Module (PCM) computer. Models with diesel engines use Transmission Control Module (TCM) computer. These computers control hydraulic line pressure, shift solenoids "A" and "B", and TCC.

Note. For testing and diagnostic procedures of electronic components, see appropriate DIAGNOSIS article.

Note. For electronic diagnosing of the torque converter clutch, see appropriate DIAGNOSIS article.

ROAD TEST

Note. Before road testing vehicle, engine and transmission must be at operating temperature. Torque converter clutch will not engage if engine coolant has not reached operating temperature.

Gear Selector Position "D" (Overdrive)

1. With gear selector in "D" (overdrive) position, steadily increase throttle pressure to accelerate vehicle. Note shift speed engagement points in 2nd gear, 3rd gear and overdrive gear. Use shift speed charts as a reference for correct shift speeds. (Scheme 2)and (Scheme 3). Also note when Torque Converter Clutch (TCC) engages while in 3rd gear or overdrive. NOTE: Ensure TCC engages in 3rd gear or overdrive during the following steps. Transmission has a Pulse Width Modulated (PWM) solenoid, which may make TCC engagement point hard to detect. If necessary, a Tech 1 scan tool may be used to indicate TCC and shift solenoid operation.
2. At vehicle speeds of 40-50 MPH, quickly depress accelerator to half open position (part throttle detent downshift). TCC should release, solenoid "A" turns off, and transmission should immediately downshift to 3rd gear.
3. At vehicle speeds of 40-50 MPH, quickly depress accelerator to wide open position (full throttle detent downshift). TCC should release, solenoids "A" and "B" turn off, and transmission should immediately downshift to 2nd gear.
4. At vehicle speeds of 40-55 MPH, release accelerator pedal while moving gear selector to "3" (3rd gear) position. TCC should release, transmission should downshift to 3rd gear, and engine braking should slow vehicle.
5. Move gear selector to "D" (overdrive) position, and accelerate to 40-45 MPH. Release accelerator pedal while moving gear selector to "2" (2nd gear) position. TCC should release, transmission should downshift to 2nd gear immediately, and engine braking should slow vehicle.
6. Move gear selector to "D" (overdrive) position, and accelerate to 30 MPH. Release accelerator pedal while moving gear selector to "1" (1st gear) position. TCC should release, transmission should downshift to 1st gear, and engine braking should slow vehicle.
7. With gear selector in "D" (overdrive) position, accelerate vehicle to overdrive gear with TCC applied. Release accelerator pedal, and lightly apply brakes. The TCC should release. Note speeds at which vehicle downshifts. (Scheme 2)or (Scheme 3).

Gear Selector Position "3" (3rd Gear)

With vehicle stopped, move gear selector to "3" (3rd gear) position. Steadily increase throttle pressure to accelerate vehicle. Note speeds at which vehicle shifts into 2nd and 3rd gears. (Scheme 2)or (Scheme 3). Ensure TCC engages while in 3rd gear.

Gear Selector Position "2" (2nd Gear)

With vehicle stopped, move gear selector to "2" (2nd gear) position. Accelerate vehicle, and note speed at which vehicle shifts from 1st gear to 2nd gear. Accelerate vehicle to 35 MPH. Transmission should not shift into 3rd gear, and TCC should not engage.

Gear Selector Position "1" (1st Gear)

With vehicle stopped, move gear selector to "1" (1st gear) position. Accelerate vehicle to 20 MPH. Transmission should not upshift, and TCC should not engage.

Scheme 2

Note. All speeds given are in transmission output shaft RPM. Speeds are based on percent of throttle position sensor opening. Use a Tech 1 or other scan tester to monitor this data.

Scheme 3

Note. All speeds given are in transmission output shaft RPM. Speeds are based on percent of throttle position sensor opening. Use a Tech 1 or other scan tester to monitor this data.

HYDRAULIC PRESSURE TESTS

1. Before performing hydraulic pressure tests, check fluid level and condition. Check manual control linkages for correct adjustment. See «GENERAL MOTORS LIGHT TRUCKS & VANS SERVICING»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#servicing-at) article. Ensure engine is properly tuned.
2. Connect a tachometer to engine and an oil pressure gauge to line pressure test port. (Scheme 4) Compare line pressure to force motor current draw. See «FORCE MOTOR VS. LINE PRESSURE»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e) table.

Note. Hydraulic pressure is controlled by pump output and regulated by computer-controlled force motor. Line pressure is boosted (pressure is doubled) by force motor in the "R" selector position.

Scheme 4

Line Pressure Check

Start engine, and access OVERRIDE FORCE MOTOR on Tech 1 scan tool. Increase force motor current in .1-amp increments. Record line pressure readings, compare to specs. See FORCE MOTOR VS. LINE PRESSURE table. If pressure recorded is incorrect, see the HIGH OR LOW LINE PRESSURE heading under SYMPTOM DIAGNOSIS .

FORCE MOTOR VS. LINE PRESSURE

REMOVAL & INSTALLATION

See GENERAL MOTORS LIGHT TRUCKS & VANS REMOVAL & INSTALLATION article.

TORQUE CONVERTER INSPECTION

Torque converter must be replaced for any of the following reasons.

1. Damage To Pump Assembly
2. Metal Particles Present in Oil
3. Leaks in Hub Weld Area
4. Crankshaft Pilot Broken Or Damaged
5. Hub Scored Or Damaged
6. Stator Failure
7. Torque Converter Imbalance
8. Engine Coolant Contamination
9. Excessive End Play

TORQUE CONVERTER END PLAY CHECK

Mount Torque Converter End Play Fixture (J-35138) and Dial Gauge (J-8001) on stand to check end play. End play should be 0-.024" (0-0.60 mm). (Scheme 5)

Scheme 5

SPEED SENSORS/REAR HOUSING

Thoroughly clean transmission exterior. Drain fluid, and remove torque converter. Place transmission in holding fixture. Remove rear extension housing. Remove speed sensors.

LOWER TRANSMISSION ASSEMBLY

Remove oil pan and oil filter. Remove accumulator assembly. Remove valve body assembly. (Scheme 45)and (Scheme 46). Remove the check balls from the case. Refer to Fig. (Scheme 59). Remove the wiring harness. Refer to Fig. (Scheme 61). Remove the parking pawl and the manual shift linkage. Refer to Fig. (Scheme 6).

Scheme 6

SERVO ASSEMBLIES

Remove servo covers and assemblies. (Scheme 44)and (Scheme 58).

Rear Band Apply Pin Selection

1. Install Band Apply Selector Pin (J-21370-10) into servo bore. (Scheme 7) Mount Band Apply Pin Selector Gauge (J-38737) and selector pin on transmission. (Scheme 8) Apply 25 ft. lbs. (34 N.m) of torque to hex nut on gauge.
2. Note which step on selector pin lines up with top edge of apply pin gauge; use this information to determine pin length. (Scheme 7)and (Scheme 9). Record length for reassembly. Pins are available in various lengths. (Scheme 9)

Scheme 7

Scheme 8

Scheme 9

END PLAY CHECKS

Using Dial Indicator (J-8001), check front and rear unit end play. (Scheme 10)and (Scheme 11). Front unit end play should be.004-.022" (.10-.56 mm). Rear unit end play should be.005-.025" (.13-.63 mm). Record measurements for reassembly reference.

Scheme 10

Scheme 11

OIL PUMP & VALVE BODY

Remove oil pump assembly cover bolts. Remove oil pump assembly, gasket and thrust washer. (Scheme 57) Remove valve body assembly. (Scheme 46)

OVERDRIVE ASSEMBLY & 4TH CLUTCH

Remove turbine shaft and overdrive assembly. (Scheme 33) Using a 40T Torx wrench, remove the 4th clutch support bolt and discard. (Scheme 49) Remove the 4th clutch snap ring and assembly. (Scheme 55)

FORWARD & DIRECT CLUTCH

Using Clutch Remover (J-38358-A), remove forward clutch assembly. (Scheme 52) Using Clutch Remover (J-38733), remove direct clutch assembly. (Scheme 51)

INTERMEDIATE CLUTCH

Remove snap ring. Remove intermediate clutch plates and front band. (Scheme 50)

CENTER SUPPORT & REAR GEAR UNIT

1. Remove center support bolt and discard. Remove snap ring. (Scheme 49) Using Gear Assembly Remover/Installer (J-38868), Adapter (J-21364-A) and Slide Hammer Handle (J-6125-B), remove gear assembly. (Scheme 48)
2. Remove rear case snap ring. (Scheme 12) Remove rear band and thrust washer. If necessary, select proper selective thrust washer based on end play measurements. See «END PLAY CHECKS»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e__end-play-checks) under TRANSMISSION DISASSEMBLY. Set thrust washer aside for reassembly.

Scheme 12

Cleaning & Inspection

Thoroughly clean transmission case with solvent and dry using compressed air. Inspect transmission case for damage to band lugs, snap ring grooves, drive sprocket bearings, interconnected or damaged oil passages and servo bores. Inspect case for stripped threads in bolt holes or casting porosity. Repair or replace case if necessary.

Inspection

DO NOT wash bands in solvent. Inspect each band assembly for heat damage, lining cracks and separation. Check band stop for damage and replace if necessary. If rear band is replaced, recheck apply pin. See SERVO ASSEMBLIES under TRANSMISSION DISASSEMBLY.

Disassembly

Remove snap rings. Separate center support, output carrier, reaction carrier and parts of rear gear unit. (Scheme 14)

Using Clutch Compressor (J-23327) and Adapter (J-38734), compress intermediate clutch springs, and remove snap ring. Separate center support from intermediate clutch assembly. (Scheme 16)

1. Inspect output carrier, reaction carrier and reaction drum for damaged teeth, scoring or warpage. Check thrust bearing for damage. Using a feeler gauge, check output carrier and reaction carrier pinion gear end play. (Scheme 13)and (Scheme 15).
2. End play should be.009-.024" (.23-.61 mm). Check for damage to reaction carrier internal gear. Ensure center support cup plug bleed hole opening is about.020" (.51 mm). (Scheme 17)

Reassembly

Using Piston Installer (J-21362), install intermediate piston to center support. (Scheme 18) Reassemble center support and rear gear unit. (Scheme 19)-22. Install new oil seal rings to center support.

Scheme 13

Scheme 14

Scheme 15

Scheme 16

Scheme 17

Scheme 18

Scheme 19

Scheme 20

Scheme 21

Scheme 22

Disassemble intermediate sprag clutch assembly. Discard the spiral snap ring. Remove the direct clutch pack. (Scheme 23) Using Clutch Compressor (J-23327) and Adapter (J-25018-A), compress direct clutch springs, and remove snap ring.

Scheme 23

Inspect all parts for wear, cracks, burned plates and scoring; replace if necessary.

1. Reassemble intermediate sprag clutch. (Scheme 24) Install new spiral snap ring. Ensure intermediate sprag rotates clockwise only. (Scheme 25)
2. Using Clutch Piston Installers (J-21362 and J-38732), install piston into direct clutch housing. Reassemble direct clutch. Direct clutch uses 5 steel plates, 5 composition plates and one dished plate. (Scheme 23)and (Scheme 26).
3. Apply 80 psi (550 kPa) of air to the reverse port. (Scheme 27) Air should bleed through direct port. Apply air pressure to direct port. Ensure piston seals do not leak. Direct clutch piston should move.121-.186" (3.07-4.72 mm).

Scheme 24

Scheme 25

Scheme 26

Scheme 27

FORWARD CLUTCH

Note. Prior to checking Forward Clutch piston movement, check identification plate attached to rear of transmission case. Units with ZBP identification are set to a different specification.

Disassemble forward clutch assembly. (Scheme 28) Using Clutch Spring Compressor (J-23327-1), compress and remove spring retainer. (Scheme 30) Remove clutch piston and seals from piston.

Inspect all clutch plates for cracks, wear, lining separation, pits or other signs of damage. Ensure forward clutch housing check ball is working. Inspect thrust washer for damage. Inspect clutch housing for damaged clutch hub, worn bushings or damaged oil seal rings.

1. Using Clutch Piston Installers (J-21362 and J-38732), install piston into forward clutch housing. Reassemble forward clutch. (Scheme 28) Install correct number of clutch plates. Refer to the «FORWARD CLUTCH PLATE APPLICATION»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e) table.
2. Apply 80 psi (550 kPa) of air to turbine shaft air port. (Scheme 29) Ensure piston seals do not leak. Check forward clutch piston movement. Forward clutch piston should move.121-.186" (3.07-4.72 mm) on all except model ZBP. On model ZBP, forward clutch piston should move.087-.110" (2.21-2.81 mm).

FORWARD CLUTCH PLATE APPLICATION

Scheme 28

Scheme 29

Scheme 30

Remove snap ring and backing plate. (Scheme 31) Remove clutch plates. Using Clutch Spring Compressors (J-23327-1 and J-38882), compress and remove spring retainer. Remove clutch piston and seals from piston.

Inspect housing and clutch plates for damaged teeth, scoring or warpage. Ensure 4th clutch housing cup plug bleed hole opening is about .020" (.51 mm).

1. Using Piston Seal Protectors (J-38731-1, J-38731-2 and J-38731-3), install piston into 4th clutch housing. Reassemble 4th clutch assembly. (Scheme 31)
2. Install snap ring. Install 4 steel and 4 composition plates. Ensure steel plate notches are indexed opposite 4th clutch bolt hole. Ensure clearance between backing plate and snap ring is.040-.100" (1.01-2.54 mm). (Scheme 32)

Scheme 31

Scheme 32

Remove overrun clutch housing from overdrive assembly. (Scheme 33) Disassemble overrun clutch. (Scheme 34)and (Scheme 41). Using Clutch Spring Compressor (J-23327) and Adapter (J-38734), compress spring retainer, and remove clutch piston. (Scheme 34) Disassemble overdrive assembly. (Scheme 41) If necessary, disassemble overdrive carrier assembly. (Scheme 39)

Inspect housing and clutch plates for damaged teeth, scoring or warpage. Inspect spring and spring retainer for damage. Inspect overdrive carrier assembly and turbine shaft for wear or damage. Replace if necessary. Ensure end play of overdrive carrier pinions is.009-.024" (.23-.61 mm). (Scheme 36)

Turbine Shaft Seal Replacement

1. Remove oil seal rings from turbine shaft. Inspect seal ring grooves for nicks or burrs. Lubricate each oil seal ring. Place Seal Protector/Installer Kit (J-38736) on turbine shaft.
2. Quickly slide each seal into ring groove when protector is in position. Use seal driver from Kit (J-38736) to push ring over seal protector. Size seal with seal sizer from Kit (J-38736); gently twist seal sizer over each seal. Leave sizer in place.

Scheme 33

Scheme 34

1. Using Piston Seal Protector (J-38729), install piston into overrun clutch housing. (Scheme 35) Reassemble overrun clutch assembly. (Scheme 34)
2. Install snap ring. Install 3 steel and 3 composition plates. Ensure clearance between backing plate and snap ring is.033-.094" (.838-2.39 mm). (Scheme 37)
3. If necessary, reassemble overdrive carrier. (Scheme 38), (Scheme 39) and (Scheme 41). Install thrust washer to overdrive carrier. (Scheme 38) To complete reassembly, install turbine shaft and overdrive carrier to overrun clutch. (Scheme 33)and (Scheme 41).

Scheme 35

Scheme 36

Scheme 37

Scheme 38

Scheme 39

Clean and air dry oil pump. Disassemble oil pump. (Scheme 40)for exploded view of pump assembly. Use caution when removing reverse boost valve snap ring. Regulator spring is under extreme pressure.

Inspect pump body for porosity, interconnected oil passages, damaged inner pump area surface or damaged machine facing. Check gears and bushings for damage.

1. Reassemble oil pump. (Scheme 40) Install oil pump gears into pump body with chamfered side down. Measure gear clearance between oil pump gears and pump body. Clearance should be.0007-.0028" (.017-.071 mm).
2. Ensure pump body mating surface is flat. Install pump cover onto body. Install cover bolts and hand tighten bolts. Install Alignment Pin (J-25025-1) into pump. Install and tighten oil pump Alignment Band (J-21368). (Scheme 43) Tighten oil pump attaching bolts.
3. To install TCC enable valve, compress spring into oil pump body, and insert a small rod into hole "A". (Scheme 42) Install spring retainer, and remove small rod.

Scheme 40

Scheme 41

Scheme 42

Scheme 43

Inspection & Reassembly

Inspect servo pistons and seals for damage or cracks. DO NOT remove seals unless replacement is required. Inspect springs for damaged coils. Replace all damaged parts, and reassemble servos. (Scheme 44)and (Scheme 58).

Scheme 44

Inspect accumulator pistons and seals for damage or cracks. DO NOT remove seals unless replacement is required. Inspect springs for damaged coils. Replace all damaged parts, and reassemble accumulators. (Scheme 45)

Scheme 45

Thoroughly clean valve body and dry with compressed air. Cover bores when removing roll pins because some valves are under pressure. Remove valves, springs and bushings, and place on a clean surface in removed order. Remove control solenoids. Remove blind hole roll pins with a drill bit. Remove servo pipe lip seals.

Clean valves, springs and bushings in solvent. NEVER use shop rags to clean valve body components. Inspect valves and bushings for scoring, nicks and scratches. Inspect springs for damaged or distorted coils. Inspect valve body casting for porosity, interconnected oil passages and damaged machined surfaces.

To reassemble valve body assembly, reverse disassembly procedure. (Scheme 47)

Scheme 46

TRANSMISSION REASSEMBLY

Note. All selective thrust washer measurements taken during disassembly must be rechecked at appropriate reassembly stage. (Scheme 62)for exploded view of internal transmission components. (Scheme 63)for lip seal location and installation direction.

1. Install rear band and thrust washer. Ensure band anchor pins engage band, and band assembly stop is in place. Install proper selective thrust washer. (Scheme 46) Install rear case snap ring. Install snap ring groove into case, with snap ring opening at 9 o'clock position. (Scheme 12)
2. Using Gear Assembly Remover/Installer (J-38868), Adapter (J-21364-A) and Slide Hammer Handle (J-6125-B), install gear assembly. (Scheme 49)
3. Install upper center support snap ring with flat side down and opening at 9 o'clock position. Using Dial Indicator (J-8001), check rear unit end play. (Scheme 11) Rear unit end play should be.005-.025" (.13-.63 mm).
4. If rear unit end play is not correct, select proper size thrust washer. See «REAR END PLAY THRUST WASHER»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e) table. If necessary, remove center support and rear unit to change selective thrust washer.
5. Using Center Support Aligner (J-23093), push center support splines against case splines (away from rear servo). Align center support with bolt hole. Using new bolt, install center support bolt. (Scheme 48) Tighten bolt to 32 ft. lbs. (43 N.m).

REAR END PLAY THRUST WASHER

Scheme 47

Scheme 48

Scheme 49

Install intermediate clutch plates (4 steel and 4 composition). (Scheme 50) Install backing plate with flat side down. Install snap ring at 9 o'clock position. Ensure clearance between clutch plates and backing plate is.040-.107" (1.02-2.72 mm). Using Clutch Plate Aligner (J-24396), align intermediate clutch assembly.

Scheme 50

Apply air pressure into center support hole to hold intermediate clutch plates in place. Using Clutch Installer (J-38733), install direct clutch assembly and front band. (Scheme 50)and (Scheme 51). Using Clutch Installer (J-38358-A), install forward clutch assembly and thrust bearing. (Scheme 52)and (Scheme 62).

Note. Check installed height of speed sensor ring (on forward clutch housing). Top of speed sensor ring to oil pump gasket surface height should be 3.85-3.89" (98.0-99.0 mm).

Scheme 51

Scheme 52

1. Install 4th clutch support (without clutch plates) into transmission case. Using 40T Torx wrench, install new 4th clutch support bolt. (Scheme 53) Tighten bolt to 12 ft. lbs. (16 N.m).
2. Remove turbine seal sizer from turbine shaft. Install turbine shaft and overdrive assembly. (Scheme 33) Ensure assembly is fully seated. Install 4th clutch plates (4 steel and 4 composition). Install steel plates with narrow tang "V" notch at 1 o'clock position in housing. (Scheme 54) Install backing plate and snap ring. Refer to Fig. (Scheme 55).

Scheme 53

Scheme 54

Scheme 55

OIL PUMP

1. Install Locating Pin (J-25025-1) at 12 o'clock position. Install oil pump gasket. (Scheme 56) Install selective thrust washer. Using Handle (J-37789), install oil pump assembly. (Scheme 57) Ensure turbine shaft spins free. Tighten oil pump mounting bolts.
2. Using Dial Indicator (J-8001), check front unit end play. (Scheme 10) Front unit end play should be.004-.022" (.10-.56 mm). If front unit end play is not correct, select proper size thrust washer. See «FRONT END PLAY THRUST WASHER IDENTIFICATION»(/chevrolet/cab-chassis-k2500/1989-2000/remont/automatic-trans/#automatic-transmission-overhaul-testing-4l80e) table. If necessary, remove oil pump assembly to change selective thrust washer.

Scheme 56

Scheme 57

FRONT END PLAY THRUST WASHER IDENTIFICATION

Install selected rear band apply pin. If necessary, check rear band apply pin using Band Apply Selector Pin (J-21370-10) and Band Apply Pin Gauge (J-38737). See SERVO ASSEMBLIES under TRANSMISSION DISASSEMBLY. Install front and rear servo assemblies. (Scheme 44)and (Scheme 58).

Scheme 58

Install parking pawl and manual linkage. (Scheme 6) Install check balls in case. (Scheme 59) Assemble and install accumulator assembly. (Scheme 45) Tighten accumulator assembly bolts in sequence. (Scheme 60) Install valve body assembly. (Scheme 46) Install lube pipe and wiring harness. (Scheme 61) Install oil pan and oil filter.

SPEED SENSORS & REAR HOUSING

Install and secure torque converter. Install rear extension housing. Install speed sensors.

Scheme 59

Scheme 60

Scheme 61

Scheme 62

Scheme 63

TRANSMISSION SPECIFICATIONS

TRANSMISSION SPECIFICATIONS

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

WIRING DIAGRAMS

Note. See appropriate wiring diagrams article.

See also:
• GENERAL MOTORS LIGHT TRUCKS & VANS TRANSMISSION SERVICING
• GENERAL MOTORS LIGHT TRUCKS & VANS REMOVAL & INSTALLATION
• OIL PUMP & VALVE BODY
• ROAD TEST
• HYDRAULIC PRESSURE TESTS
• SYMPTOM DIAGNOSIS
• FORCE MOTOR VS. LINE PRESSURE
• END PLAY CHECKS